Machines exist to apply various coatings to printed circuit panels. The most common are machines to apply solder to printed circuit panels as set forth in U.S. Pat. Nos. 4,465,014; 4,563,974 and 4,608,941. Various masking techniques are also known to print circuits on printed circuit panels.
Printed circuit panels with multiple electrical circuits interconnecting to other printed circuit panels or to components outside the panel require a number of electroplated connector tabs, or fingers, to be provided as part of the overall panel. These connector tabs, usually located at the edge of the panel, insert into a multi-lead female connector, either (1) mounted to a corresponding printed circuit panel or (2) attached to an external component via a multi-conductor cable to provide electrical connection.
A thin layer of gold is electroplated onto these connector tabs during fabrication of the panel to provide maximum conductivity at the tab/connector interface. This is done after the panel's internal circuitry is complete and before its discrete components are mounted and soldered in place.
Circuit portions of the panel surrounding the tab areas must be masked during the electroplating of gold to prevent damage from the chemicals used and to confine gold deposition only to the tabs themselves. Selective manual application of a specially formulated and expensive plater's tape is at present the primary means of accomplishing the tab masking.
When all of the tab groups on a panel are placed in-line along one edge of the panel, masking the circuit area surrounding these groups can be done by applying a continuous strip of thin pressure-sensitive tape along the common top edge of the tab area. However, connector tabs are grouped and spaced differently on different printed circuit panels and often are recessed from the panel edge, thereby complicating the application of plater's tape. Such tape must then be applied in multiple strips along the panel edge and may require patching small pieces of tape to the circuit areas around recessed tab groups. When taping is completed, the panels are run between high pressure rollers to insure maximum adhesion of the tape to both front and back panel surfaces and maximum conformance to the irregularities produced by circuit traces.
After gold plating the connector tabs, the tape is removed by hand using a razor blade, knife or other tool and the panel edges are chemically cleaned to remove all residue of tape adhesive. The entire manual taping/detaping operation is tedious, time consuming and labor intensive. A method is needed to eliminate this time consuming step and accelerate the masking process.